Large sealed ignitron-tube



2 Sheets-Sheet. l

0 c m A L O c R LARGE SEALED IGNITRON-TUBE Filed. Jan. 14, 1955- new 4, 1956 A. P. COLAIACO LARGE SEALED IGNITRON-TUBE 2 Sheets-Sheet 2 Filed Jan. 14, 1955 lNVENTOlR August P. Coloioco WITNESSES ATTORNEY United States Patent O LARGE SEALED IGNITRON-TUBE August P. Colaiaco, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 14, 1955, Serial No. 481,787

2 Claims. (Cl. 313-19) My invention relates to large sealed metal ignitrontubes, or other vapor-arc tubes having evacuated metal containers. Such tubes, as now known, require several servicings throughout their lives, these servicings being spaced a certain number of years apart, depending upon the individual tube, and being required because of internal failures, resulting from many causes, including the limited lives of various parts, the accumulation of sludge 011 the bottom of the tube, and the deterioration of the vacuum within the tube. My present invention relates to a novel means and structure for facilitating such periodic servicing. It is characterized by a permanent or non-removable metal cathode-header, having one or more smaller removable headers in it, for periodically servicing the tube.

An exemplary form of embodiment of my invention is shown in the accompanying drawing, in which,

Fig. l is a vertical sectional view through the tube, and

Fig. 2 is a transverse sectional view, above the cathode-pool, on a section-plane indicated at 11-41 in Fig. 1.

My vapor-arc tube has an evacuated metal container, and my invention was primarily developed for a sealed tube, that is, a tube which operates without pumping during its operation. Essentially, so far as my present invention is concerned, the evacuated metal container comprises an upright cylindrical side-wall 2 having a cooling-jacket 3, a cathode-header 4 having a coolingjacket 5, and an annular anode-header 6.

Thetube also has an anode-structure 7, which is insulatedly carried by the anode-header 6. The illustrated anode-structure 7 is a polyanode structure, such as is broadly covered by an application of Bohn and Boyer, Serial No. 424,384, filed April 20, 1954. it comprises a plurality of graphite anodes which are supported from a plate 9, which is supported from an upper metal closure-member 9A for the anode-structure 7. This anode closure-member 7, in the illustrated embodiment, is insulatedly supported in two different ways, from the annular anode-header 6 of the evacuated metal container. The vacuum-tightness of the container is provided by an upright glass cylinder 98, having its top and bottom ends secured, by glass-to-rnetal seals 9C, to the closure-member 7 and the hole-portion of the anodeheader 6, respectively. The necessary structural strength is provided by an outer cylindrical main-anode porcelain or other insulating structure it), which is mounted on the annular anode-header 6 so as to support the upper metal closure-member 9A.

As shown, this main-anode porcelain it) is mounted on asbestos-cloth gaskets 11, surrounding a central opening in the anode-header 6; and the porcelain it is clamped to the anode-header 6 by a flexible clampingring 12, which is the invention of John L. Boyer, William W. Wise and myself.

Each anode 3 is provided with its own graphite shield 14, and the plurality of shield-structures support a cen- 2,773,21 l Patented Dec. 4, 1956 trally depending graphite deionizing anode 15, in the illustrated form of construction.

The tube also has a cathode-pool 16, which is usually mercury, and which is disposed in a depressed central portion of the cathode-header 4. The cathode-construction usually also includes a centrally disposed quartz arc-centering ring 17, which is carried by the cathodeheader 4 at the level of the mercury pool 16, and, above that, a graphite battle 18, which is carried by a plurality of supporting-legs 19 which are secured to the top of the cathode-header 4.

The tube also contains one or more limited-life members which are supported within the tube, from the cathode-header As shown in Fig. 2, there are four such limited-life members in the illustrated tube. One of these limited-life members, as shown in Fig. 2, is an auxiliary anode 21, which is supported, in an offset position, from the top of an upstanding lead-rod 22. The other three illustrated limited-life members, as shown in Fig. 2, are ignitors 23, each of which is supported, in an offset manner, from the top of its own lead-rod 24. The ignitors 23 usually have a more limited life than the auxiliary anode 21, or other parts of the tube, which are subject to failure, and hence it has become customary to supply more than one ignitor 23. Ordinarily, the ignitors are used, one at a time, until a failure occurs, whereupon the ignitor-connections, at the bottom of the tube, are transferred to another ignitor, which is then used till it fails, and so on, the object being to prolong or extend the necessary times between servicings of the tube, and also to so correlate the designs of the various tube-parts that, whenever a servicing operation is required, it will be about time to thoroughly service all of the internal parts of the tube.

In the large sealed ignitron-tubes for which my invention was primarily designed, various considerations pointed to the desirability of joining the cathode-header 4 in an essentially permanent manner to the side-wall 2, as shown in the drawing, wherein the side-wall 2 and the cathode-header 4 are spun in a cup-like formation, from a single sheet of steel. It is not possible or practicable, therefore, to remove the cathode-header 4 from the side-wall 2, for one of these servicing operations.

in accordance with my invention, the cathode-header 4 has one or more smaller depending tubular portions 25, one of which is shown in Fig. 1. Each of these depending tubular portions 25 has an open lowermost end, which extends free of the cooling-jacket 5 of the cathode-header 4. Each of the depending tubular portions 25 is provided with its own small separate auxiliary header 26, which has a depending peripheral flange 27, fitting telescopically within its depending tubular portion 25 of the cathode-header 4. In accordance with my invention, I provide a relatively removable joint be tween the extreme lowermost ends of each telescopically fitting flange 27 and its depending tubular portion 25, as indicated by the weld 28. This is a known removable form of hermetic welded joint, which .has been used before with removable headers, but not with small auxiliary headers 26 which are provided in the cathodeheader 4, as in my present invention. When the re' movable Weld 28 is to be removed, in order to remove the auxiliary header 26, the depending telescoping parts 25 and 27, which are welded at their lowermost ends, are ground off until the weld is broken, so that the auxiliary header 26 can be removed. The free or accessible lower ends of the telescoping portions 25 and 27 are of sufiicient axial or vertical length, so that there is enough material to make it possible to perform such grinding-operations several times, so as to permit several servicing operations, within the life of the equipment.

The removable auxiliary header 26, or each of said headers if there are more than one, is provided with one or more of the lead-rods 22 or 24, which support the several limited-life members 21 and 23. Each of these leadrods, such as the rod 24 in Fig. 1, extends through the top of its auxiliary header 26, through a suitable insulating support 29, which is hermetically sealed to the lead-rod 24 and to the auxiliary header 26. This insulating support 29 is preferably surrounded by a shield 30 which protects it from the heat of the arc.

in order to make possible a thorough servicing operation, when one of my ignitron-tubes comes into the shop for servicing, I prefer to provide a removable sealing joint between the anode-header 6 and the top of the side-wall 2 of the tube. To this end, I have shown, in Fig. 1, a removable anode-header construction such as has been essentially known and used in previous forms of ignitron-tubes. In this construction, the anode-header 6 is provided with an upwardly extending peripheral flange 31, which fits telescopically within the upper end of the side-wall 2, and the topmost ends of said telescopically fitting flange 31 and side-wall 6 are hermetically joined by a removable weld 32, which is similar to the previously described weld 28.

Any suitable liquid-circulating means may be used, for cooling the cooling-jackets 3 and 5. Usually, water is used as the cooling medium. In the illustrated form of embodiment of my invention, as shown in Fig. 1, water is lead in, at the bottom of the tube, into the center of the cooling-jacket of the cathode-header 4, as shown at the inlet 33. From the periphery of this jacket 5, a pipe-connection (not shown) leads up to a cooling-coil. 34, which is provided inside of the tube, immediately above the cathode-pool 16. From this cooling-coil 34, a pipe-connection 35 leads to the bottom of the coolingjacket 3 of the side-wall 2. The cooling-water is discharged from the top of this jacket 3 through an outlet 36.

Any suitable bafliing-means may be used, in the jackets 3 and 5, for directing the circulation of the coolingwater. In the particular form of construction which I have shown for the side-wall cooling-jacket 3, the cylindrical side-wall 2 and the outer cylindrical metal jacketwall 37 are joined, in a mutually strengthening formation, by means of a flat horizontal spirally wound metal strip 38, of which successive convolutions are spaced one above the other, and the spiral convolutions 38 are rigidly mechanically connected to the two concentric cylindrical walls 2 and 37, so as to provide a strong cellular construction which avoids the necessity for using exceptionally heavy-gauge material for the side-wall 2 of the tube, to withstand the atmospheric pressure due to the evacuation of the tube, according to an invention of William W. Wise, described and claimed in an application Serial No. 550,111, filed November 30, 1955.

While I have illustrated my invention in a single form of construction, which is now preferred, I wish it to be understood that I am not limited to all of the illustrated details of construction, since various parts may be replaced by equivalent structures, or certain features may be omitted, and others added, without departing from the essential spirit of the invention.

I claim as my invention:

1. A vapor-arc tube having an evacuated metal container comprising an upright cylindrical side-wall having a cooling-jacket, a cathode-header having a cooling-jacket, and an anode-header; said tube also having an anodestructure which is insulatedly carried by the anodeheader, a cathode-pool in a central portion of the oathode-header, and a limited-life member which is supported within the tube from the cathode-header; said cathode-header being relatively permanently joined to the side-wall; said cathode-header having a smaller depending tubular portion having an open lowermost end which extends free of the cooling-jacket of the cathodeheader, a small separate auxiliary header for said depending tubular portion of the cathode-header, said auxiliary header having a depending peripheral flange, fitting telescopically within its depending tubular portion of the cathode-header, a relatively removable joint between the extreme lowermost end of the telescopically fitting flange and its depending tubular portion, and a support-rod, insulatedly carried by said auxiliary header, for supporting said limited-life member within the tube.

2. The invention as defined in claim 1, characterized by said anode-header having an upwardly extending peripheral flange, fitting telescopically within the upper end of the side-wall, and a relatively removable joint between the topmost ends of said telescopically fitting flange and side-wall.

References Cited in the file of this patent UNITED STATES PATENTS 2,214,596 Rose Sept. 10, 1940 2,217,421 Scott Oct. 7, 1940 2,431,153 White Nov. 18, 1947 2,532,836 Cupido Dec. 5, 1950 

